Which larva has probably given origin to chordates through paedomorphosis ?

Options

A. Auricularia
B. Bipinnaria
C. Brachiolaria
D. pluteus

Answer

To answer the question "Which larva has probably given origin to chordates through paedomorphosis?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Paedomorphosis**:
- Paedomorphosis is a biological phenomenon where juvenile traits are retained in the adult form of an organism. This means that the adult organism does not undergo the typical metamorphosis that leads to a completely different adult form.

2. **Identify the Relevant Larvae**:
- We need to examine different types of larvae and their characteristics to find which one may have contributed to the evolution of chordates through paedomorphosis.

3. **Examine Auricularia Larva**:
- Auricularia is a larval form found in certain echinoderms, specifically in Asteroidea (starfish) and Holothuroidea (sea cucumbers).
- This larva exhibits features that are reminiscent of chordates, such as having 4 to 5 ciliated bands, a developed mouth, and a gut.

4. **Compare with Other Larvae**:
- **Bipinaria**: This larva is also from echinoderms but does not show the features associated with paedomorphosis and lacks a skeletal system.
- **Brachiolaria**: Similar to Bipinaria, this larva does not exhibit the modified features that would suggest a connection to chordates.
- **Pluteus**: This larva, found in sea urchins, also lacks the characteristics that would link it to chordate evolution.

5. **Conclusion**:
- Based on the characteristics and the concept of paedomorphosis, the Auricularia larva is the one that likely gave rise to chordates due to its retention of juvenile traits that resemble those of chordates.

### Final Answer:
The larva that has probably given origin to chordates through paedomorphosis is **Auricularia**.

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